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This page displays the COHERENT manpage for chmod() [Change file-protection modes].
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chmod() -- System Call (libc) Change file-protection modes #include <sys/stat.h> chmod(file, mode) char *file; int mode; chmod() sets the mode bits for file. The mode bits include protection bits, the set-user-id bit, and the sticky bit. mode is constructed from the logical OR of the mode constants declared in the header file stat.h, as follows: S_ISUID Set user identifier on execution S_ISGID Set group identifier on execution S_ISVTX Save file on swap device (``sticky bit'') S_IRUSR Read permission for owner S_IWUSR Write permission for owner S_IXUSR Execute permission for owner S_IRGRP Read permission for members of owner's group S_IWGRP Write permission for members of owner's group S_IXGRP Execute permission for members of owner's group S_IROTH Read permission for other users S_IWOTH Write permission for other users S_IXOTH Execute permission for other users For directories, some protection bits have a different meaning: write permission means files may be created and removed, whereas execute permission means that the directory may be searched. The save-text bit (or ``sticky bit'') is a flag to the system when it executes a shared for of a load module. After the system runs the program, it leaves shared segments on the swap device to speed subsequent reinvocation of the program. Setting this bit is restricted to the superuser (to control depletion of swap space which might result from overuse). Only the owner of a file or the superuser may change its mode. See Also creat(), libc, stat.h POSIX Standard, §5.6.4 Diagnostics chmod() returns -1 for errors, such as file being nonexistent or the invoker being neither the owner nor the superuser.